On 28/09/2018 14:28, Aldo Mazzeo wrote: > I was trying to translate a very high virtual address (like > 0x0010000000000001) to physical on x86-64 with *paging disabled*. The > problem is that the obtained physical page is 0 because PG_ADDRESS_MASK > is applied to the pte in the virtual to physical to translation > (see target/i386/helper.c:842 in the 2.12.1 branch), cutting out the > high bits in the virtual address.
Hi, x86_64 is never active with paging disabled, so physical addresses with paging disabled are always 32-bits. In addition, physical addresses on x86 are constrained to 52-bits, so that address is invalid. Paolo > I tried to track back when this mask was introduced in the equation, > and I found the commit e7e898a76aa00e2238b119ed2910442b1c3cacdd which > replaces PHYS_ADDR_MASK with PG_ADDRESS_MASK and moves the line in a > section of code that is executed even if paging is disabled. In my > opinion, PG_ADDRESS_MASK should not be applied when paging is disabled, > but I would like to have some expert's opinion on this. >
